This invention relates to hindered ortho-alkylated phenyl phosphites which are effective in stabilizing organic materials particularly plastics, polymers and resins as well as mineral and synthetic fluids and oils.
Organic polymeric materials such as plastics and resins and lubricating and mineral oil are subject to thermal, oxidative and photodegradation. A great variety of stabilizers are known in the art for stabilizing various substrates. Their effectiveness varies depending on the causes of degradation and the substrate stabilized. It is known that many stabilizers that are very effective long term antioxidants are relatively poor process stabilizers which require stabilization of the substrate, against thermal degradation for a short time, but at a relatively high temperature. Many stabilizers are relatively incompatible with the substrates which causes problems during the lift of a product and lessens the stabilizer's effectiveness. Some stabilizers are either too volatile or thermally or hydrolytically unstable to be practical as commercial stabilizers.
In Japanese No. 73/41,009 (CA, 81, 121856g (1974)), a non-hindered phenylphosphonite and a non-hindered phenylthiophosphonite are disclosed as heat stabilizers for ABS, PVC, polyolefins and other polymeric substances.
Diphenylphosphonites, diphenylene bis-phosphonites and terphenylene bis-phosphonites are described in U.S. Pat. No. 3,825,629 as stabilizers for organic materials. These compounds are structurally different from the instant compounds especially in reference to the diphenyl or terphenyl moiety directly attached to the P atom in these molecules.
Thermostabilized liner polyesters containing small amounts of diphenyl phenylphosphonite are claimed in U.S. Pat. No. 3,609,118. This patent contains a very broad generic reference to phenylphosphonites with no subgeneric disclosures and with only diphenyl phenylphosphonite being exemplified.
U.S. Pat. No. 3,809,676 and U.S. Pat. No. 3,978,020 disclose generically some phosphonites of structures related to those of the instant invention, but do not exemplify or specifically mention the specific genus of phosphonites of this invention. These references respectively pertain to thermally stable flame retardant polycarbonates containing a phosphonite or phosphinite in combination with a barium, calcium or cerium alkanoate or carbonate and to thermally stable polycarbonates containing a phosphonite and an epoxide compound.
The instant phosphonites are more effective as stabilizers than the closest prior art phosphonites. They also surprisingly exhibit far superior hydrolytic stability compared to many of the previously known phosphonites. This superior hydrolytic stability permits the instant phosphonites to be used in those myriad of cases where water pickup is a disadvantage and presents practical end use problems in the product composition being stabilized. One such example is in polyester fibers where the use of stabilizers which hydrolyze and/or are hygroscopic cause undesired swelling of the fiber and ancillary deficiencies.
It was found that the instant phosphonites presumedly because of their structural character overcome these deficiencies of the prior art phosphonites and thus combine excellent stabilizing efficacy with hydrolytic stability and the absence of secondary performance problems related to hydrolysis and/or the water pickup of the prior art phosphonite stabilizers. Indeed, the instant compounds possess a combination of desired properties including outstanding stabilization efficiency especially at high temperatures, and not only do not detract from light stabilization, but actually exhibit light stability properties, acceptable hydrolytic stability and good color in stabilized compositions.